Grille shutter device

Abstract

A grille shutter device includes a frame body having an inlet and airfoil-shaped flaps. The flaps are configured to open or close the inlet by rotating in forward and reverse directions around respective rotary shafts. A section of each flap between an upstream edge and a downstream edge is referred to as a first section. A section of each flap between the first section and the downstream edge is referred to as a second section. Each flap includes a symmetrical airfoil portion. The symmetrical airfoil portion is shaped to be symmetrical with respect to a chord line. A thickness of the symmetrical airfoil portion in a direction that is orthogonal to a direction in which the chord line extends and a direction in which the rotary shaft extends, gradually increases from the upstream edge toward the first section and gradually decreases from the first section toward the second section.

What is claimed is: 
     
         1 . A grille shutter device configured to open or close an opening provided at a front section of a vehicle, the grille shutter device comprising:
 a frame body having an inlet through which air flows; and   airfoil-shaped flaps, each having a rotary shaft that is rotationally supported by the frame body, the flaps being configured to open or close the inlet by rotating in forward and reverse directions around the respective rotary shafts, wherein   an edge of each of the flaps on an upstream side and an edge of each of the flaps on a downstream side in a flow direction of the air when the flaps are located in an open position, at which the flaps open the inlet, are referred to as an upstream edge and a downstream edge,   a section of each of the flaps between the upstream edge and the downstream edge is referred to as a first section and a section of each of the flaps between the first section and the downstream edge is referred to as a second section,   each of the flaps includes a symmetrical airfoil portion that forms a portion of the flap between the upstream edge and the second section,   the symmetrical airfoil portion is shaped to be symmetrical with respect to a chord line that connects the upstream edge to the downstream edge, and   a thickness of the symmetrical airfoil portion in a direction that is orthogonal to a direction in which the chord line extends and a direction in which the rotary shaft extends, gradually increases from the upstream edge toward the first section and gradually decreases from the first section toward the second section.   
     
     
         2 . The grille shutter device according to  claim 1 , wherein
 the downstream edge has a planar downstream end face that is orthogonal to the chord line.   
     
     
         3 . The grille shutter device according to  claim 1 , wherein
 the flaps each include an asymmetrical airfoil portion that is continuously formed downstream of the symmetrical airfoil portion and is asymmetrical in shape relative to the chord line, and   the asymmetrical airfoil portion includes a contact surface, wherein, when the flaps are in the closed position to close the inlet, the contact surface of each of the flaps is in contact with an outer surface of the symmetrical airfoil portion of an other one of the flaps.   
     
     
         4 . The grille shutter device according to  claim 3 , wherein
 two curved surfaces protruding in a direction away from the chord line are respectively provided on opposite sides of the symmetrical airfoil portion in a thickness direction of the symmetrical airfoil portion, and   the contact surface of each of the flaps is curved along the curved surface of the other one of the flaps.